Plastic shortenings are generally produced by appropriate thermal and mechanical treatment of a mixture of several components. In the production of a conventional plastic shortening, lightly hydrogenated vegetable oils and intermediate hardened oils are blended with fully hydrogenated hardstock in varying proportions to produce a product which is approximately 85% oil and 15% solid at room temperature. The quality and texture of shortenings depend on incorporated gas, plasticity and consistency and solid to liquid ratio. These physical characteristics are determined by the crystal phase of the fats used and the method of preparation.
Although the beta phase crystalline form of triglyceride is a more thermodynamically stable crystalline phase than the beta prime phase, plastic shortenings having a solid phase predominantly in the beta prime form are usually used because the beta phase crystalline form shortenings have historically tended to have a soupy, highly fluid consistency and/or a translucent appearance. Lard and tallow are predominantly in the beta phase, but contain high levels of saturated fat. It is well known in the art that beta prime crystals, if present, have the capacity to form a rigidly interlocking structure when suspended in a liquid component at sufficient concentration. However, plastic shortenings containing beta prime solid triglycerides are noticeably deficient in their ability to withstand storage at temperatures ranging from 90-100.degree. F. for periods of 1-3 months or so without appreciable change in their performance and appearance. Some types of beta prime plastic shortenings tend to stiffen or firm excessively and thus become difficult to blend with other constituents in normal food recipes. Shortening blends of vegetable oils and fat derived from animals are also beta prime phase plastic shortenings. However, these shortenings are also high in saturates and tend to be firm. Because both the beta phase plastic shortening and the beta prime plastic shortening lack desired features, a compromise often has been made in preparing conventional plastic shortenings. Generally shortenings crystallized in the beta prime phase are thought to be preferable for providing the most uniform product appearance and stability over varying temperature ranges.
Conventional plastic shortenings comprise intermediate-melting, partially hydrogenated semi-solid fat commonly called "intermediate-melting fat" dispersed in the liquid oil, an unhardened or partially hydrogenated liquid oil commonly called "base oil", and a fully hydrogenated solid fat commonly called "hardstock". In general, the method of attaining the beta prime crystal form desired for plastic shortenings is to use a suitable beta prime tending highly hydrogenated or saturated hardstock. Conventional beta prime tending hardstocks contain triglycerides that may undergo polymorphic transformations and crystal size changes on processing and storage and/or on temperature variations under stress conditions. This transformation results in a shortening which has a poor appearance, poor volume and poor performance. Further, the hydrogenation process causes transisomeric forms of the mono and polyunsaturates to form. There is some concern that trans isomers and saturated fats in the diet may be linked to high levels of cholesterol in the blood (hypercholesterolemia).
The use of vegetable oils and margarine for cooking and baking are thought to be an effective means for lowering dietary intake of saturated fats and trans fatty acids. A typical vegetable oil has about 2.0 grams of saturates and 0 grams of trans per serving. Conventional margarine contains about 2.0 grams of saturated fat and 2.5 grams of trans fatty acids per serving as compared to vegetable plastic shortenings which typically contain from about 2.5 to about 3.5 grams of saturated fat and from about 2.0 to about 2.5 grams of trans fatty acids per serving. While vegetable oils and margarines are desirable from a health aspect, vegetable oil is often less desirable for baking due to lack of performance e.g. "poor creamability". Margarines are less desirable for frying. In pan frying, margarines brown and burn, and in deep frying they are totally unusable, due to the reaction of the protein and sugars required by the margarine standard of identity.
Low trans isomer fat products (e.g., certain margarines and shortenings) are generally formed from a blend of interesterified fats, unsaturated vegetable oils, saturated vegetable oils and mixtures thereof. While these processes produce a low trans fat product, the product is often high in saturated fats. Other methods focus on reducing the saturated level fats by utilizing the trans-isomer content of the unsaturated fatty acids to provide functional solids for the shortening or margarine. A way of producing a lower saturate, lower trans shortening would be to utilize genetically bred oil with low saturates level and no trans isomers. However these oils tend to be very expensive, and availability of the oils is limited.
It has surprisingly been found that by using an unhydrogenated base oil low in saturates and low in trans, a mixture of a beta tending hardstock and a beta prime tending hardstock both having an IV of less than 10, an antioxidant, an emulsifier and an inert gas, in combination with a unique processing method that an effective baking and frying shortening can be made. This unique shortening has reduced levels of saturates and trans fatty acids. This is accomplished predominantly by reducing the level of trans fatty acids and saturates in the base oil by using an unhydrogenated base oil and an antioxidant, which provides oxidative stability, a highly efficient structuring system and high levels of inert gas dispersed in the shortening. The antioxidant controls undesirable oxidation of unhydrogenated oils. The beta prime tending hardstock is responsible for obtaining the desired beta prime like behavior even though the shortening is in the beta phase. The beta tending hardstock stabilizes the shortening in the beta phase without destroying the desired beta prime like performance, thereby achieving the desired stability and performance of a plastic shortening. Accordingly, the low saturate, low trans stable plastic shortening of the present invention has from about 1.5 grams to about 2.5 grams of saturates, and about 0 grams to about 0.5 grams trans fatty acid isomers per serving as compared to conventional shortening which contain about 2.5 grams to about 3.5 grams of saturates, and about 1.5 to about 2.5 grams of trans fatty acid isomers per serving.
It is therefore an object of the present invention to provide a low saturate, low trans, beta stable plastic shortening suitable for use in preparation of a broad range of applications consisting of, but not limited to shortenings, peanut butter stabilizers, cosmetics, confections, frostings and baked goods and margarine.
It is also the object of the present invention to provide a beta stable plastic shortening exhibiting superior product appearance, texture, and stability, and to provide a method for its preparation.
It is also the object of the present invention to provide a beta stable plastic shortening having a uniform consistency and which does not have a tendency to firm over a wide range of temperatures. It is stable to temperature cycling.
Another object of this invention is to provide a method of preparation of a low saturate, low trans, plastic shortening having the above described characteristics.
These and other objects will become apparent from the following detailed description. All percentages herein are by weight unless otherwise specified.